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Hot, with a Dry Pattern Emerging in the North

May 28, 2018

Hot, with a Dry Pattern Emerging in the North:

Nearly through the month of May now and a pronounced dry pattern has emerged in the northern part of Minnesota. Some climate stations are 1.5 to 3.0 inches below normal for the month and 3 to 5 inches below normal since April 1st. Over 50 percent of the state’s landscape is abnormally dry, while portions of Beltrami, Lake of the Woods, Roseau, and Koochiching Counties are in moderate drought according to the U.S. Drought Monitor.

Persistent warmer than normal temperatures for the balance of May will exacerbate the dryness, as daytime highs consistently reach 85 to 100 degrees F in many parts of the state. In fact based on the forecasts through May 31 the state will record one of the hottest months of May in history ranking with 1977, 1934, and 1988. Though statewide temperature records have not been broken, Fairmont, Tracy, Worthington, Canby, and Madison have all seen the mercury rise to 100 degrees F this month (on the 27th). The Twin Cities will likely record its 2nd hottest May , surpassed only by that of 1934 when a temperature of 106 degrees F closed the month on the 31st. For the Twin Cities only three other Mays have brought 4 consecutive days with temperatures in the 90s F, and those were 1874, 1934, and 1988. It is likely the Twin Cities will record 6 consecutive days in the 90s F during the current Heat Wave. More about May Heat Waves can be found at the Minnesota State Climatology Office web site.

Widespread showers and thunderstorms may help offset this warmth, but I suspect by the end of the month more counties in Minnesota may fall into the moderate drought category as well. The outlook for June favors continued warm temperatures but equal chances for above or below normal precipitation.

Heat as a Health Risk for School Children

A recent Facebook post by Joe Nathan, former Director of the Center for School Change at the Humphrey Institute made me think more about climate change and school safety in Minnesota. Besides severe weather (tornadoes, severe thunderstorms, flash flooding), heat is one of the most serious threats to the health of school children, in many areas the most serious. Fortunately in our Minnesota climate history we have recorded relatively few episodes of this, with sporadic days of 90 degree F heat in May and September. The frequency of extreme heat during the school year is likely to continue to increase as our climate changes, and we already have evidence for this emerging in the trends of recent years. Since 2000 there have been 7 Mays that have brought two or more days of 90°F temperatures, and 7 Septembers (including the record-setting hot one of 2016) that have produced similar frequency of 90 degree F heat.

The current Heat Wave episode around the state has brought 5-6 consecutive days of 90 degree F temperatures to scores of communities, with 100°F reached in a number of western Minnesota locations. Many of these days occurred over the Memorial Weekend when schools were closed. Nevertheless, many schools are not air conditioned and structurally designed so that they store a great deal of heat. In this context, when schools resume on May 29th, it is likely that the buildings will be quite hot and uncomfortable, most likely to the extent that children will not be able to be as attentive as needed in the classroom, and perhaps will need reminders about drinking water to stay hydrated, and not overdoing exercise at recess. In this context there should be more administrative attention paid to policy guidelines for limited recess, earlier than normal dismissal, nurse staffing, school cancellations, etc. These threats to children’s health are very real and should be seriously considered……..many scientists like myself would simply say this is an important “climate adaptation” that should not be ignored.

Weekly Weather Potpourri:

TropicalCyclone Sagar in the Gulf of Aden made landfall in Somalia last week. It is quite rare for the Horn of Africa to be affected by tropical cyclones. According to weather records only two other tropical cyclones have made landfall in this part of Africa, one in 2015 and one in 1984. Sagar brought heavy rains and flash flooding to parts of Somalia which has been mostly in drought over the past five years.

Speaking of tropical cyclones, Cyclone Mekunu was heading for the coasts of Yemen and Oman in the Middle East this week. It is a significant storm with large bands of heavy rain, wind gusts over 100 mph and sea waves of 25-30 feet. It is expected to make landfall by Saturday.

TropicalStorm Alberto will bring strong winds, high seas, and heavy rain to the Florida Panhandle this weekend. Rainfall totals of 8 to 12 inches are possible for parts of Florida, and some areas will see winds well over 50 mph.

MPR listener question:

Seeing the forecast for a hot weekend made me wonder how often do temperatures reach 90 degrees F or warmer in the Twin Cities over Memorial Weekend?

Answer:

Over the past 145 years in the Twin Cities climate record the daily maximum temperature has reached 90 degrees F on at least one day of the Memorial Weekend 20 times, or about one year in every 7. So this is somewhat unusual. The consecutive days of temperatures of 90 degrees F or higher is much more unusual.

Twin Cities Almanac for May 25th

The average MSP high temperature for this date is 72 degrees F (plus or minus 9 degrees F standard deviation), while the average low is 52 degrees F (plus or minus 8 degrees F standard deviation).

Average dew point for May 25th is 47°F; the maximum dew point on this date is 72°F in 1916; and the minimum dew point on this date is 23°F in 1998.

All-time state records for May 25th:

The all-time state high temperature for today's date is 100 degrees F at Luverne (Rock County) in 1967; the all-time state low for today's date is 19 degrees F at Tower (St Louis County) in 1983. The all-time state record precipitation for this date is 4.32 inches at St James (Watonwan County) in 1953. Record snowfall is 4.0 inches at Baudette (Lake of the Woods County) in 1970.

Past Weather Features:

Strong thunderstorms brought 2-5 inches of rain to many parts of southern Minnesota on May 25, 1953. Some county roads in Pipestone and Watonwan Counties were washed out and had to be repaired in the middle of the planting season.

An unusual storm brought 2-4 inches of snow across portions of Beltrami, Koochiching, and Lake of the Woods Counties over May 25-26, 1970. Some fishermen on Lake of the Woods had to bring their boat ashore as they could not see in the heavy snowfall, with 4 inches falling in just over 2 hours.

By far the warmest May 25th in state history was in 1967 when over 30 communities reported daytime highs of 90 degrees F or greater. There was a risk of wildfires too as winds were gusty and relative humidity was very low that day.

Widespread frosts occurred in northern and western parts of Minnesota on May 25, 1983. Many climate stations reported morning lows ranging from 20 degrees F to 30 degrees F. Where crop damage was significant, fields were replanted.

Outlook:

A hot conclusion to May. Many areas will see daytime highs in the 90s over the weekend, perhaps the mid 90s on Sunday. Chance for showers and thunderstorms by late Monday and next Tuesday and Wednesday with daytime temperatures dropping back into the 80s F, still warmer than normal for this time of year.